build: modernize Go usage

This commit modernizes Go usage. This was done with:

go run golang.org/x/tools/gopls/internal/analysis/modernize/cmd/modernize@latest -fix -test ./...

Then files needed to be `go fmt`ed and a few comments needed to be
restored.

The modernizations include replacing

- if/else conditional assignment by a call to the built-in min or max functions added in go1.21
- sort.Slice(x, func(i, j int) bool) { return s[i] < s[j] } by a call to slices.Sort(s), added in go1.21
- interface{} by the 'any' type added in go1.18
- append([]T(nil), s...) by slices.Clone(s) or slices.Concat(s), added in go1.21
- loop around an m[k]=v map update by a call to one of the Collect, Copy, Clone, or Insert functions from the maps package, added in go1.21
- []byte(fmt.Sprintf...) by fmt.Appendf(nil, ...), added in go1.19
- append(s[:i], s[i+1]...) by slices.Delete(s, i, i+1), added in go1.21
- a 3-clause for i := 0; i < n; i++ {} loop by for i := range n {}, added in go1.22

lib/cache/cache_test.go

@@ -18,7 +18,7 @@ var (
 
 func setup(t *testing.T) (*Cache, CreateFunc) {
 	called = 0
-	create := func(path string) (interface{}, bool, error) {
+	create := func(path string) (any, bool, error) {
 		assert.Equal(t, 0, called)
 		called++
 		switch path {
@@ -289,7 +289,7 @@ func TestDelete(t *testing.T) {
 }
 
 func TestDeletePrefix(t *testing.T) {
-	create := func(path string) (interface{}, bool, error) {
+	create := func(path string) (any, bool, error) {
 		return path, true, nil
 	}
 	c := New()
@@ -317,7 +317,7 @@ func TestDeletePrefix(t *testing.T) {
 
 func TestCacheRename(t *testing.T) {
 	c := New()
-	create := func(path string) (interface{}, bool, error) {
+	create := func(path string) (any, bool, error) {
 		return path, true, nil
 	}
 
@@ -353,10 +353,10 @@ func TestCacheRename(t *testing.T) {
 func TestCacheFinalize(t *testing.T) {
 	c := New()
 	numCalled := 0
-	c.SetFinalizer(func(v interface{}) {
+	c.SetFinalizer(func(v any) {
 		numCalled++
 	})
-	create := func(path string) (interface{}, bool, error) {
+	create := func(path string) (any, bool, error) {
 		return path, true, nil
 	}
 	_, _ = c.Get("ok", create)